1. Field of the Invention
The invention generally relates to multipurpose vehicles, and more particularly, to vehicles that are configured to travel by both air and land.
2. Description of the Related Art
Since shortly after the invention of the first aircraft, the flying automobile has been pursued as the next generation of revolutionary vehicle. A flying automobile, frequently referred to as a roadable aircraft, has usually been envisioned as a "fixed wing" aircraft. A few concepts, however, include rotary wings and operate as autogyro type aircraft with an autorotating rotor providing lift, and powered propellers delivering forward thrust when the craft is airborne for forward flight. The autogyro rotor is typically powered for a short time to allow a jump takeoff.
Over the last fifty years, several concepts have emerged for implementing roadable aircraft. Some concepts were implemented as flying prototypes, and in a few cases, even received regulatory approval, such as from the now-superseded Civil Aeronautics Administration. No such roadable aircraft, however, has achieved any significant economic success in either the commercial or the military market for several reasons. For example, existing concepts of flying automobiles, being predominantly fixed wing aircraft, require at least a minimum-length runway to take off and land. Consequently, such vehicles require access to an airport or comparable facility to fly. The necessity of runway facilities eliminates many of the advantages of roadable aircraft, particularly the ability to take off and land at remote and random locations.
In addition, fixed wing roadable aircraft almost exclusively derive lift from the fixed wing and propulsion from an engine/propeller combination. To make road travel practical, the wing and propeller must be removed or repositioned. Various designs propose leaving these components at the airport, towing them behind the vehicle like a trailer, or folding or retracting them into the body of the car. Each of these configurations suffers the problem of either not providing an appropriate method of retracting and housing the wing and propeller in the body of the vehicle or requiring the removal of the propeller or wing. Assembling and removing the wing and propeller is an inconvenient, time-consuming process. In addition, aircraft regulating authorities, such as the Federal Aviation Administration, typically disapprove of any activities that involve assembling or disassembling structurally necessary aircraft components by any person other than a licensed Aircraft and Powerplant (A and P) mechanic. This further complicates the process of removing and reattaching the wing and propeller assembly, thus increasing the cost and inconvenience of the roadable aircraft.
In addition to conventional fixed-wing concepts, roadable, jump-takeoff autogyro-type vehicles have been implemented. These vehicles require shorter runways than conventional fixed wing aircraft, and are therefore preferable in many applications. Like fixed wing aircraft, however, autogyro aircraft cannot hover. As a result, autogyro-type roadable aircraft are similarly restricted to minimum-length runway sites. In addition, these aircraft also suffer the problems associated with removing and folding the rotary wing and propeller while the craft is in the road configuration.
In sum, previously developed concepts for roadable aircraft fail to effectively fulfill several practical requirements. A successful roadable aircraft should not require runway facilities, should be easy and quick to use, and should require no special training to convert between road and flight configurations.